Decoding the function of intron retention in the spatiotemporal regulation of TERT RNA

• Applicant: Dr. Gabrijela Dumbovic
• Subject Area: Cell Biology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 562550297

Subcellular compartmentalization of the transcriptome plays a critical role in regulating gene expression. Intron retention (IR), a form of alternative splicing, often results in the nuclear retention of the RNA. Telomerase Reverse Transcriptase (TERT) encodes the catalytic and limiting component of telomerase, the ribonucleoprotein complex responsible for telomere elongation. Telomerase is found ubiquitously throughout the eukaryotic lineage as a successful solution to the end-replication problem. TERT expression is confined to proliferative cells, such as those in fetal development and stem cells, while it is transcriptionally silenced in most somatic cells. This silencing limits the replicative capacity of cells, leading to senescence once telomeres reach a critically short length. However, in many cancers, TERT is aberrantly reactivated, enabling malignant cells to proliferate indefinitely. Therefore, the precise regulation of TERT expression is essential for maintaining telomere homeostasis and cellular lifespan. Our studies show that TERT RNA is predominantly retained in the nucleus, where it is unavailable for translation. TERT exhibits one of the highest and most conserved IR events among protein-coding RNAs. These data suggest an RNA-mediated mechanism that regulates TERT RNA availability for translation and, consequently, telomere maintenance. However, although TERT is required for telomerase activity, the mechanism and role of IR in the regulation of telomerase assembly and telomere maintenance remain unknown. Our interdisciplinary research project aims to elucidate the mechanism and function of IR in TERT RNA in hiPS cells, specifically how it modulates its subcellular localization and translation dynamics over subcellular space and time. Using innovative single-molecule RNA imaging methods for tracking subcellular RNA kinetics, biochemical analyses of RNA-protein interactions and CRISPR, we will: (1) Investigate the molecular mechanisms regulating TERT IR in hiPS cells; (2) Track the real-time kinetics of TERT splicing and export during the cell cycle; and (3) Elucidate the function of TERT IR. Additionally, we will explore broader transcriptome programs regulated by the identified mechanism, providing new insights into the regulation of gene expression at the RNA level.

• DFG Programme: Research Grants